Regulation Effect of Lactobacillus johnsonii on Chickens infected with Ascaridia galli

Ascaridia galli remains highly prevalent in modern poultry systems and is mainly controlled with chemical anthelmintics, which drive drug resistance and residue concerns. We previously found that A. galli infection depleted Lactobacillus johnsonii in the chicken gut, suggesting a probiotic control strategy. In this study, eighty 1-day-old chicks were randomly assigned to four groups: control, A. galli + PBS, PBS + L. johnsonii, and A. galli + L. johnsonii. Chicks were infected orally with 1,000 A. galli eggs and/or given L. johnsonii daily for 14 days. A. galli infection significantly impaired growth performance, whereas L. johnsonii supplementation partially restored body weight gain and feed efficiency. Macroscopic and histopathological analyses showed that A. galli severely disrupted intestinal barrier integrity, suppressed barrier-related gene expression, triggered oxidative-stress-mediated apoptosis, and up-regulated pro-inflammatory cytokines. In contrast, L. johnsonii mitigated intestinal injury and inflammation by normalizing these molecular responses. 16S rRNA sequencing further demonstrated that L. johnsonii reshaped the A. galli-disturbed gut microbiota, accompanied by a marked reduction in intestinal worm burden. These findings indicate that L. johnsonii is a promising green and safe biological strategy for sustainable control of A. galli in poultry.